E stop resistor size

[Denver]

How do I determine the resistor size for the e stop circuit ?. On page 45 of the 2 x 45 a manual it shows the limit / home and e stop wiring. I take it the wiring is the same for all. The resistor shown as R2 I take it is the one I need to add. My wiring to the control area will be 20 mtrs long. If you could explain how to go about working this out it would be appreciated.
Many Thanks

[Basicmicro Support]

The longer the wire, the harder you need the pullup to be to prevent accidental tripping of the signal. I usually recommend 10k to 1k for a pullup resistor. For that long a wire I'd go with the 1k pullup.